JP3379125B2 - Exhaust gas purification catalyst - Google Patents
Exhaust gas purification catalystInfo
- Publication number
- JP3379125B2 JP3379125B2 JP00249293A JP249293A JP3379125B2 JP 3379125 B2 JP3379125 B2 JP 3379125B2 JP 00249293 A JP00249293 A JP 00249293A JP 249293 A JP249293 A JP 249293A JP 3379125 B2 JP3379125 B2 JP 3379125B2
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- catalyst
- lanthanum
- gas purification
- lean
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000003054 catalyst Substances 0.000 title claims description 41
- 238000000746 purification Methods 0.000 title claims description 19
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 45
- 239000007789 gas Substances 0.000 claims description 34
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 21
- 229910052746 lanthanum Inorganic materials 0.000 claims description 14
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 12
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 12
- 239000002131 composite material Substances 0.000 claims description 11
- 229910052697 platinum Inorganic materials 0.000 claims description 10
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 9
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 9
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 8
- 150000002910 rare earth metals Chemical class 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 7
- 230000007547 defect Effects 0.000 claims description 7
- 229910052763 palladium Inorganic materials 0.000 claims description 7
- 229930195733 hydrocarbon Natural products 0.000 claims description 5
- 150000002430 hydrocarbons Chemical class 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 229910052723 transition metal Inorganic materials 0.000 claims description 5
- 150000003624 transition metals Chemical class 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 13
- 239000000446 fuel Substances 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000010948 rhodium Substances 0.000 description 6
- 229910052703 rhodium Inorganic materials 0.000 description 5
- 229910052684 Cerium Inorganic materials 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 125000004429 atom Chemical group 0.000 description 3
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000006255 coating slurry Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- -1 That is Chemical compound 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229910052705 radium Inorganic materials 0.000 description 2
- HCWPIIXVSYCSAN-UHFFFAOYSA-N radium atom Chemical compound [Ra] HCWPIIXVSYCSAN-UHFFFAOYSA-N 0.000 description 2
- 230000001603 reducing effect Effects 0.000 description 2
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- KWGRBVOPPLSCSI-WPRPVWTQSA-N (-)-ephedrine Chemical compound CN[C@@H](C)[C@H](O)C1=CC=CC=C1 KWGRBVOPPLSCSI-WPRPVWTQSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910020785 La—Ce Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- FJWGYAHXMCUOOM-QHOUIDNNSA-N [(2s,3r,4s,5r,6r)-2-[(2r,3r,4s,5r,6s)-4,5-dinitrooxy-2-(nitrooxymethyl)-6-[(2r,3r,4s,5r,6s)-4,5,6-trinitrooxy-2-(nitrooxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-3,5-dinitrooxy-6-(nitrooxymethyl)oxan-4-yl] nitrate Chemical compound O([C@@H]1O[C@@H]([C@H]([C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O)O[C@H]1[C@@H]([C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@@H](CO[N+]([O-])=O)O1)O[N+]([O-])=O)CO[N+](=O)[O-])[C@@H]1[C@@H](CO[N+]([O-])=O)O[C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O FJWGYAHXMCUOOM-QHOUIDNNSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 150000004700 cobalt complex Chemical class 0.000 description 1
- FZKDURCLMTYEER-UHFFFAOYSA-N cobalt lanthanum Chemical compound [Co].[Co].[Co].[La] FZKDURCLMTYEER-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- MPOKJOWFCMDRKP-UHFFFAOYSA-N gold;hydrate Chemical compound O.[Au] MPOKJOWFCMDRKP-UHFFFAOYSA-N 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910003446 platinum oxide Inorganic materials 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 150000003839 salts Chemical group 0.000 description 1
- 230000009291 secondary effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000010938 white gold Substances 0.000 description 1
- 229910000832 white gold Inorganic materials 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Landscapes
- Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は、排気ガス浄化用触媒に
関し、さらに詳しくは、酸素過剰下の排気ガス、すなわ
ち、排気ガス中に含まれる一酸化炭素、水素および炭化
水素等の還元性物質を完全に酸化させるのに必要な酸素
量よりも過剰な量の酸素が含まれている排気ガス中のＮ
Ｏx(窒素酸化物）を効率よく浄化する排気ガス浄化用触
媒に関する。
【０００２】
【従来の技術】従来より、自動車の排気ガス浄化用触媒
として、排気ガス中の一酸化炭素（ＣＯ）および炭化水
素（ＨＣ）の酸化と、窒素酸化物（ＮＯx ）の還元とを
同時に行うことにより排気ガスを浄化する排気ガス浄化
用三元触媒が数多く知られている。このような触媒とし
ては、例えば、コージュライトなどの耐熱性担体にγ−
アルミナスラリーを塗布し、焼成し、Ｐｄ、Ｐｔ、Ｒｈ
などの貴金属を担持させた触媒が典型的である。
【０００３】ところで、これら排気ガス浄化用触媒は、
エンジンの設定空燃比によりその性能が大きく左右さ
れ、特に、希薄混合雰囲気、すなわち空燃比の大きいリ
ーン側では、燃焼後の排気ガス中の酸素量が多くなり、
酸化作用が活発に、還元作用が不活発になる。逆に、空
燃比の小さいリッチ側では、燃焼後の排気ガス中の酸素
量が少なくなり、酸化作用が不活発に、還元作用が活発
になる。
【０００４】一方、近年、資源問題、地球温暖化の観点
から省エネルギーが求められ、自動車の低燃費化の要請
が強く、ガソリンエンジンにおいては効率的な燃焼面か
ら希薄燃焼（リーンバーン）が注目されている。この希
薄燃料では、通常走行時になるべく酸素過剰の混合気で
燃焼させるリーン側での運転が行われており、リーン側
でも十分にＮＯx を浄化できる触媒が望まれていた。
【０００５】そこで、これら問題を解決するため、この
ような酸素過剰雰囲気下の自動車排気ガス浄化触媒とし
て、一酸化炭素、炭化水素の酸化と窒素酸化物の還元を
同時に行う触媒が種々提案されている。例えば、アルミ
ナ担体に白金を担持させて成るＰｔ／Ａｌ2 Ｏ3 もその
一例であるが、実用上充分な浄化率を示すものではな
く、特に過渡状態時（市街地走行模擬状態時）において
問題がある。
【０００６】一方、本出願人等は過渡状態時（市街地走
行模擬状態時）において、ＮＯｘ浄化率を高めるために
アルミナ担体に白金およびランタン酸化物（Ｌａ
2 Ｏ3 ）を担持した触媒を提案した（特願平３−３４４
７８１）。この触媒は定常走行のような、空燃比Ａ／Ｆ
がリーンの状態ではＮＯｘは一部がＨＣにより還元され
て窒素になり、残りの未反応ＮＯｘは触媒中のＬａ2 Ｏ
3 上に吸着され、車両加速時や車両停止時のＡ／Ｆが理
論Ａ／Ｆの際にはＬａ2 Ｏ3 上に吸着されたＮＯｘが浄
化される。
【０００７】
【発明が解決しようとする課題】しかしながら、アルミ
ナ担体にＰｔおよびＬａ2 Ｏ3 を担持した触媒には、必
ずしも必要十分な浄化率が得られないという問題があ
る。この理由は必ずしも明確ではないが、リーンＡ／Ｆ
時のＬａ2 Ｏ3 のＮＯｘの吸着量や理論Ａ／Ｆ時のＮＯ
x の放出速度が不足しているためと推察される。
【０００８】従って、本発明の目的は、酸素過剰雰囲気
下において、排気ガス中の一酸化炭素、炭化水素及び窒
素酸化物の浄化効率に優れた排気ガス浄化用触媒を提供
することにある。また、本発明の他の目的は、希薄燃焼
型自動車の走行状態のように、理論空燃比近傍からオー
バーリーン（Ａ／Ｆ＝約２３程度）までの範囲内で頻繁
にガス組成が変化するような使用状態において、排気ガ
ス中の一酸化炭素、炭化水素及び窒素酸化物を共に効率
よく浄化する排気ガス浄化用触媒を提供することにあ
る。
【０００９】
【課題を解決するための手段】本発明に従えば、希薄燃
焼エンジンから排出される排気ガス中の一酸化炭素、炭
化水素及び窒素酸化物を同時に浄化する排気ガス浄化用
触媒において、多孔質体からなる担体に（ｉ）白金又は
パラジウム並びに（ii）ランタンと希土類金属及び遷移
金属の中から選ばれた少なくとも１種の金属との格子欠
陥を有する複合酸化物を担持せしめて成り、リーン時に
は窒素酸化物をランタンに吸着せしめ、ストイキ時及び
リッチ時にその窒素酸化物を放出して排気ガスを浄化す
る排気ガス浄化用触媒が提供される。
【００１０】本発明に係る排気ガス浄化用触媒は、前記
した通り、多孔質体からなる担体に、（ｉ）白金又はパ
ラジウム及びこれらに加えて任意的なロジウム並びに
（ii）ランタンと希土類金属及び遷移金属の中から選ば
れた少なくとも一種の金属との格子欠陥を有する複合酸
化物を担持せしめて成る。本発明において用いることの
できる多孔質担体としては、アルミナ、ゼオライト、ジ
ルコニア、シリカアルミナ、シリカ等をあげることがで
きる。これらの多孔質担体の種類及び物性については特
に限定はなく、従来から触媒用として使用されていた任
意の多孔質担体を使用することができる。また、これら
の多孔質担体はコージュライト、耐熱金属合金等からな
るハニカム基体にコートして用いても良い。
【００１１】本発明に係る排気ガス浄化用触媒におい
て、前記した多孔質担体に担持される白金及び／又はパ
ラジウムの担持量には特に限定はないが、一般には多孔
質体１リットル当り０．１〜５ｇ原子、好ましくは０．
５〜２．５ｇ担持される。本発明の好ましい態様では白
金又はパラジウムに加えて、ロジウムを担持させると、
ＮＯx とＣＯ又はＨＣとの反応が促進されるので好まし
い。好ましいＲｈの担持量は多孔質体１リットル当り
０．０５〜０．５ｇ原子である。
【００１２】本発明に係る排気ガス浄化用触媒は、多孔
質担体に更に（ａ）ランタンと（ｂ）希土類金属（例え
ば、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｔｂ）及び／又は
遷移金属（例えば、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｒ、Ｎｉ、Ｃ
ｕ）との格子欠陥を有する複合酸化物を担持させる。こ
のような複合酸化物の代表的なものとしては、（Ｃｅ
1-X ＬａX ）Ｏ3 及び（Ｌａ1-X ＣｅX )2Ｏ3 （式中、
ｘ＝0.01〜 0.5）などのＬａ−Ｃｅ系複合酸化物、Ｌａ
ＭＯ3 及び（Ｌａ1-X ＳｒX ）ＭＯ3 （式中、Ｍ＝Ｃ
ｏ、Ｍｎ、Ｆｅ、Ｃｒ）などのＬａＭＯ3 型ペロブスカ
イト、Ｌａ2 ＭＯ4及び（Ｌａ2-X ＳｒX ）ＭＯ4 （式
中、Ｍ＝Ｃｕ、Ｎｉ）などをあげることができる。かか
る複合酸化物の担持量には特に限定はないが、多孔質担
体１リットル当り、好ましくは０．０５〜１．０ mol、
更に好ましくは０．２〜０．５ mol担持させるのが良
い。
【００１３】本発明に係る排気ガス浄化用触媒は、通
常、多孔質体、好ましくはアルミナ、シリカアルミナ、
ゼオライトに、ランタン及び希土類金属（又は遷移金
属）の水溶性化合物の水溶性を被覆、焼成し、次に、こ
れに白金もしくはパラジウム（又は更にロジウム）の水
溶性化合物の水溶液を被覆、焼成することによって製造
することができる。
【００１４】本発明に係る排気ガス浄化用触媒を用いて
排気ガスを浄化するにあたっては、通常の方法で実施す
ることができ、排気ガスを触媒層に導入する空間速度(S
V)にも特に限定はなく、例えば 300,000〜10,000hr-1の
範囲が好ましく、また触媒層温度にも特に制限はない
が、 200〜 800℃程度の温度が好ましい。
【００１５】
【作用】ランタンとセリウムなどの希土類又はコバルト
などの遷移金属と複合酸化物では、ランタンと例えばセ
リウムとの酸化数が異なるため複合酸化物を形成すると
格子欠陥が生じ、本発明の知見によれば、このような格
子欠陥がＮＯx の触媒上への吸着、放出作用を促進し、
ＮＯx の浄化率が向上するものと思われる。また、本発
明の触媒を用いれば、二次的な効果として、例えばアル
ミナ担体にＰｔおよびＬａ2 Ｏ3 を担持した従来の触媒
の他の問題点である耐熱性や耐イオウ被毒性も向上させ
ることができる。これは、複合酸化物の生成によりアル
ミナとランタンとの反応を抑制し、さらに生成する硫酸
塩の分解を容易にするためであると考えられる。
【００１６】即ち、従来のＰｔ及びＬａ2 Ｏ3 をアルミ
ナ担体に担持させた触媒では、アルミナとランタンとの
反応で、ＬａＡｌＯ3 が生成して触媒上でのＰｔの高分
散状態が損なわれ、またＬａのＮＯ吸収作用がなくなる
ため、ＮＯx 浄化率が低下するものと想定されていた
が、本発明ではＬａＡｌＯ3 の生成が効果的に抑制され
るためにかかる問題が起こらない。本発明によれば、リ
ーン時に、排ガス中のＮＯやＳＯ2 がＬａにとり込まれ
てＬａ（ＮＯ3 ）3 及びＬａ2(ＳＯ4 ）3 となる。次に
ストイキ時やリッチ時には、Ｌａ（ＮＯ3 ）3 が分解し
て、ＮＯ2 の放出浄化がおこるが、Ｌａ2(ＳＯ4)3 は分
解せず、触媒上に蓄積していく。ところが本発明ではＣ
ｅなどの希土類金属やコバルトなどの遷移金属の存在に
より、Ｌａ 2(ＳＯ4)3 がＬａとＳＯ2 とに分解されるの
でＬａのＮＯ吸収作用が生じるようになる。なお、この
作用はＬａと、希土類金属や遷移金属がそれぞれ単独で
存在していても生ぜず、両者が格子欠陥を有する複合酸
化物の形で存在していることが肝要である。
【００１７】
【実施例】以下、実施例によって本発明を更に説明する
が、本発明の範囲をこれらの実施例に限定するものでは
ない。
【００１８】例１〜８
担持量の異なる、貴金属（Ｐｔ、Ｐｄ、Ｒｈ）／ランタ
ン・セリウム複合酸化物（又はランタン、コバルト複合
酸化物）／Ａｌ2 Ｏ3 触媒を製造し、性能評価試験を行
った。
〔触媒調製１〕活性アルミナ粉末１００重量部にアルミ
ナゾル（アルミナ含有量：１０重量％）７０重量部、４
０重量％硝酸アルミニウム水溶液１５重量部、および水
３０重量部を加えて攪拌混合し、コーティング用スラリ
ーを調製した。このコーティング用スラリーを用い、コ
ージェライト製ハニカム担体に常法に従ってアルミナコ
ートを施した。次にこの担体を硝酸ランタンと硝酸セリ
ウムの混合水溶液に浸漬し、乾燥後、６５０℃で１時間
焼成した。次いで、所定の濃度のジニトロジアンミン白
金水（又は硝酸パラジウム）溶液と硝酸ロジウム混合水
溶液に浸漬し、乾燥後３００℃、１時間焼成して表１の
触媒 No.１，２，３及び４（実施例）を得た。尚、比較
のためにランタンのみ又はセリウムのみを担持した触媒
No.６及び７（比較例）も調製した。
【００１９】〔触媒調製２〕活性アルミナ粉末１００重
量部にアルミナゾル（アルミナ含有量：１０重量％）７
０重量部、４０重量％硝酸アルミニウム水溶液１５重量
部、および水３０重量部を加えて攪拌混合し、コーティ
ング用スラリーを調製した。このコーティング用スラリ
ーに（Ｌａ0.8 、Ｓｒ0.2)ＣｏＯ3 粉末を加え混合攪拌
した。なお、このときの（Ｌａ0.8 、Ｓｒ0.2)ＣｏＯ3
粉末混合量は、触媒完成時に触媒Ｉリットル当たり０．
３ｍｏｌの（Ｌａ0.8 、Ｓｒ0.2)ＣｏＯ3 が担持される
様に調製した。このコーティング用スラリーを用い、コ
ージェライト製ハニカム担体にアルミナコートを施し
た。乾燥後、６５０℃で１時間焼成した。次いで、所定
の濃度のジニトロジアンミン白金水溶液と硝酸ロジウム
混合水溶液に浸漬し、乾燥後３００℃、１時間焼成し
て、表１、触媒 No.５（実施例）を得た。
【００２０】
【表１】【００２１】〔活性評価〕上で調製した各触媒を希薄燃
焼エンジンの排気系に配置し、エンジンをＡ／Ｆ＝２２
の条件で運転して定常状態における触媒の浄化率を測定
した。また、過渡状態としてＡ／Ｆ＝１４．５（ストイ
キ）とＡ／Ｆ＝１８（リーン）とを６分周期で変化させ
ることにより行った。耐久試験は、入りガス温度７００
℃でＡ／Ｆ＝１４．５とＡ／Ｆ＝１８を１：９の割合で
１０分周期で交互に変化させて、１００時間行い、この
後の活性を評価した。結果を表２に示す。表２の結果よ
り明らかなように、本発明の触媒は初期浄化性能及び耐
久浄化性能ともに優れている。
【００２２】
【表２】【００２３】
【発明の効果】以上説明したように、格子欠陥を有する
複合酸化物を担持させた本発明触媒によれば、ＬａのＮ
Ｏの吸収放出作用を著しく促進することができる。DETAILED DESCRIPTION OF THE INVENTION
[0001]
The present invention relates to an exhaust gas purifying catalyst.
More specifically, exhaust gas with excess oxygen,
That is, carbon monoxide, hydrogen and carbon
Oxygen required to completely oxidize reducing substances such as hydrogen
N in exhaust gas containing an excessive amount of oxygen
Exhaust gas purification catalyst that efficiently purifies Ox (nitrogen oxide)
Medium.
[0002]
2. Description of the Related Art Conventionally, catalysts for purifying exhaust gas from automobiles have been used.
As carbon monoxide (CO) and hydrocarbons in exhaust gas
Oxidation of nitrogen (HC) and reduction of nitrogen oxides (NOx)
Exhaust gas purification that purifies exhaust gas by performing simultaneously
Many three-way catalysts are known. Such a catalyst
For example, γ-
Alumina slurry is applied and fired, and Pd, Pt, Rh
A catalyst supporting a noble metal such as a noble metal is typical.
Incidentally, these exhaust gas purifying catalysts are:
Its performance greatly depends on the set air-fuel ratio of the engine.
In particular, lean mixed atmospheres, that is, those with a large air-fuel ratio
On the other hand, the amount of oxygen in the exhaust gas after combustion increases,
Oxidation is active and reduction is inactive. Conversely, the sky
On the rich side where the fuel ratio is small, the oxygen in the exhaust gas after combustion
Reduced amount, oxidizing action is inactive, reducing action is active
become.
On the other hand, in recent years, resource issues and global warming
Demand for energy savings and demand for lower fuel consumption of automobiles
Is a strong and efficient combustion aspect for gasoline engines?
Lean burn has attracted attention. This rare
With thin fuel, use a mixture of oxygen excess as much as possible during normal driving.
The operation on the lean side to burn is performed, and the lean side
However, a catalyst that can sufficiently purify NOx has been desired.
[0005] To solve these problems,
Catalyst for purifying automobile exhaust gas under such an oxygen-rich atmosphere
To oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides.
Various catalysts to be performed simultaneously have been proposed. For example, aluminum
Pt / Al with platinum supported on carrierTwoOThreeAlso
This is an example, but it does not show a sufficient purification rate for practical use.
Especially in the transient state (simulated city driving)
There's a problem.
[0006] On the other hand, the present applicant and the like in the transition state (city driving)
To improve the NOx purification rate in the simulation mode)
Platinum and lanthanum oxide (La
TwoOThree(Japanese Patent Application No. 3-344).
781). This catalyst has an air-fuel ratio A / F as in a steady running.
Is lean, NOx is partially reduced by HC
And the remaining unreacted NOx becomes La in the catalyst.TwoO
ThreeA / F during vehicle acceleration and vehicle stoppage
In the case of A / F, LaTwoOThreeNOx adsorbed on the top is purified
Be converted to
[0007]
SUMMARY OF THE INVENTION However, aluminum
Pt and La on carrierTwoOThreeIs required for catalysts carrying
There is a problem that a sufficient and sufficient purification rate cannot be obtained.
You. The reason is not always clear, but lean A / F
La at timeTwoOThreeNOx adsorption amount and NO at theoretical A / F
It is presumed that the release speed of x was insufficient.
Accordingly, an object of the present invention is to provide an oxygen-excess atmosphere
Below, carbon monoxide, hydrocarbons and nitrogen in the exhaust gas
Providing an Exhaust Gas Purification Catalyst with Excellent Oxide Purification Efficiency
Is to do. Another object of the present invention is to provide a lean burn
From the vicinity of the stoichiometric air-fuel ratio
Frequent within the range up to burlean (A / F = about 23)
Exhaust gas in a usage condition where the gas composition changes
Efficiency of carbon monoxide, hydrocarbons and nitrogen oxides in gas
To provide an exhaust gas purification catalyst that purifies well
You.
[0009]
According to the present invention,Lean burn
Emitted from the burning engineCarbon monoxide and charcoal in exhaust gas
Exhaust gas purification for simultaneous purification of hydrogen hydride and nitrogen oxides
In the catalyst, (i) platinum or
Palladium and (ii) lanthanum and rare earth metals and transitions
Lack of lattice with at least one metal selected from metals
The composite oxide withWhen lean
Makes nitrogen oxides adsorb on lanthanum,
Purifies exhaust gas by releasing its nitrogen oxides when rich
ToAn exhaust gas purification catalyst is provided.
The exhaust gas purifying catalyst according to the present invention is characterized in that
As described above, (i) platinum or
Radium and in addition to these optional rhodium and
(Ii) Lanthanum, selected from rare earth metals and transition metals
Complex acid having lattice defect with at least one selected metal
On the substrate. Of the present invention
Porous carriers that can be used include alumina, zeolite,
Luconia, silica alumina, silica, etc.
Wear. Regarding the types and physical properties of these porous carriers,
There is no limitation on the
Any porous carrier can be used. Also these
The porous carrier is made of cordierite, heat-resistant metal alloy, etc.
May be used after being coated on a honeycomb substrate.
The catalyst for purifying exhaust gas according to the present invention
And the platinum and / or palladium supported on the porous carrier described above.
The amount of supported radium is not particularly limited, but is generally porous.
0.1 to 5 g atoms, preferably 0.1 to 0.5 g atoms per liter of the solid body.
5 to 2.5 g are carried. In a preferred embodiment of the invention, white
In addition to gold or palladium, when carrying rhodium,
It is preferable because the reaction between NOx and CO or HC is promoted.
No. The preferred amount of supported Rh is per liter of the porous body.
0.05-0.5 g atom.
The exhaust gas purifying catalyst according to the present invention has a porous structure.
(A) lanthanum and (b) rare earth metal (for example,
For example, Ce, Pr, Nd, Sm, Eu, Tb) and / or
Transition metals (eg, Co, Mn, Fe, Cr, Ni, C
A composite oxide having a lattice defect with u) is supported. This
Typical examples of composite oxides such as (Ce
1-XLaX) OThreeAnd (La1-XCeX)TwoOThree(Where
x = 0.01-0.5) La-Ce based composite oxide, La
MOThreeAnd (La1-XSrX) MOThree(Where M = C
o, Mn, Fe, Cr)ThreeType perovska
It, LaTwoMOFourAnd (La2-XSrX) MOFour(formula
And M = Cu, Ni). Heel
There is no particular limitation on the loading amount of the composite oxide,
Preferably 0.05 to 1.0 mol per liter of body,
More preferably, 0.2 to 0.5 mol is supported.
No.
[0013] The exhaust gas purifying catalyst according to the present invention is generally used.
Usually, a porous body, preferably alumina, silica alumina,
Lanthanum and rare earth metals (or transition gold)
The water-soluble compound of the genus) is coated and calcined, and then
Platinum or palladium (or even rhodium) water
Manufactured by coating and baking an aqueous solution of a soluble compound
can do.
Using the catalyst for purifying exhaust gas according to the present invention
When purifying exhaust gas, use a normal method.
The space velocity (S
V) is not particularly limited, for example, 300,000 to 10,000 hr.-1of
The range is preferable, and the catalyst layer temperature is not particularly limited.
However, a temperature of about 200 to 800 ° C is preferable.
[0015]
[Function] Lanthanum and rare earth such as cerium or cobalt
Lanthanum and complex oxides
When the composite oxide is formed due to the different oxidation number with helium
Lattice defects occur, and according to the knowledge of the present invention, such cases
Child defects promote NOx adsorption and release on the catalyst,
It is thought that the purification rate of NOx is improved. In addition,
The use of bright catalysts has a secondary effect, for example,
Pt and La on Mina carrierTwoOThreeConventional catalyst loaded with
It also improves the other problems of heat resistance and sulfur poisoning.
Can be This is due to the formation of composite oxides.
Sulfuric acid that suppresses the reaction between mina and lanthanum and further forms
This is considered to be to facilitate the decomposition of the salt.
That is, conventional Pt and LaTwoOThreeThe aluminum
In a catalyst supported on a carrier, alumina and lanthanum
In reaction, LaAlOThreeIs generated and the Pt concentration on the catalyst increases.
Dispersion state is impaired and La NO absorption effect is lost
Therefore, it was assumed that the NOx purification rate would decrease.
However, in the present invention, LaAlOThreeGeneration is effectively suppressed
Such a problem does not occur. According to the present invention,
NO and SO in exhaust gasTwoIs taken into La
La (NOThree)ThreeAnd LaTwo(SOFour)ThreeBecomes next
At the time of stoichiometry or rich, La (NOThree)ThreeBreaks down
And NOTwoEmission purification occurs, but LaTwo(SOFour)ThreeIs a minute
Without understanding, it accumulates on the catalyst. However, in the present invention, C
e and rare earth metals and transition metals such as cobalt
Than La Two(SOFour)ThreeIs La and SOTwoWill be broken down into
Then, the NO absorption effect of La comes to occur. Note that this
The action is La and rare earth metal and transition metal are each independently
A complex acid that does not occur even if it exists and both have lattice defects
It is important that they exist in the form of chloride.
[0017]
The present invention will be further described with reference to the following examples.
However, the scope of the present invention is not limited to these examples.
Absent.
[0018]Examples 1 to 8
Precious metals (Pt, Pd, Rh) / Lanta with different loading amounts
Cerium composite oxide (or lanthanum, cobalt composite
Oxide) / AlTwoOThreeManufacture catalysts and conduct performance evaluation tests
Was.
[Catalyst preparation 1] Aluminum was added to 100 parts by weight of activated alumina powder.
70 parts by weight of Nasol (alumina content: 10% by weight), 4
15 parts by weight of 0% by weight aqueous aluminum nitrate solution and water
Add 30 parts by weight, stir and mix, slurry for coating
Was prepared. Using this coating slurry,
-Alumina coated on a jellyite honeycomb carrier
Was applied. Next, the carrier was lanthanum nitrate and cellulose nitrate
650 ° C for 1 hour
Fired. Then, a predetermined concentration of dinitrodiammine white
Gold water (or palladium nitrate) solution and rhodium nitrate mixed water
After immersion in a solution, drying and baking for 1 hour at 300 ° C.,
Catalyst Nos. 1, 2, 3, and 4 (Examples) were obtained. In addition, comparison
Supported only lanthanum or only cerium
Nos. 6 and 7 (Comparative Examples) were also prepared.
[Catalyst preparation 2] 100 weights of activated alumina powder
Alumina sol (alumina content: 10% by weight)
0 parts by weight, 15% by weight of 40% by weight aqueous solution of aluminum nitrate
And 30 parts by weight of water, and stir and mix.
A slurry for polishing was prepared. This coating slurry
-(La0.8, Sr0.2) CoOThreeAdd powder and stir
did. At this time, (La0.8, Sr0.2) CoOThree
The mixing amount of the powder was set at 0.
3 mol of (La0.8, Sr0.2) CoOThreeIs carried
Prepared in the same manner. Using this coating slurry,
-Alumina coated on honeycomb carrier made of gelite
Was. After drying, baking was performed at 650 ° C. for 1 hour. Then, predetermined
Dinitrodiammine platinum aqueous solution and rhodium nitrate at different concentrations
After immersion in a mixed aqueous solution, drying and baking at 300 ° C for 1 hour
Thus, Table 1, Catalyst No. 5 (Example) was obtained.
[0020]
[Table 1][Evaluation of activity] Each of the catalysts prepared above
A / F = 22 placed in the exhaust system of the firing engine
Operating under the above conditions and measuring the purification rate of the catalyst in the steady state
did. Also, as a transient state, A / F = 14.5 (stoichiometry)
G) and A / F = 18 (lean) at 6-minute intervals
It was done by doing. The endurance test was performed with the gas temperature 700
At A / F = 14.5 and A / F = 18 at a ratio of 1: 9
Performed for 100 hours, alternating with a 10 minute cycle,
Later activity was evaluated. Table 2 shows the results. Table 2 shows the results.
As is clear, the catalyst of the present invention has an initial purification performance and
Excellent purification performance.
[0022]
[Table 2][0023]
As described above, it has lattice defects.
According to the catalyst of the present invention supporting a composite oxide, N of La
The absorption and release action of O can be remarkably promoted.
フロントページの続き (56)参考文献 特開 平２−218439（ＪＰ，Ａ) 特開 平４−27435（ＪＰ，Ａ) 特開 昭57−63133（ＪＰ，Ａ) 特開 昭63−77543（ＪＰ，Ａ) 特開 平５−220395（ＪＰ，Ａ) 特開 平６−262040（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B01J 21/00 - 37/36 B01D 53/86 F01N 3/28 Continuation of the front page (56) References JP-A-2-218439 (JP, A) JP-A-4-27435 (JP, A) JP-A-57-63133 (JP, A) JP-A-63-77543 (JP) JP-A-5-220395 (JP, A) JP-A-6-262040 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) B01J 21/00-37/36 B01D 53/86 F01N 3/28
Claims (1)
ス中の一酸化炭素、炭化水素及び窒素酸化物を同時に浄
化する排気ガス浄化用触媒において、多孔質体からなる
担体に（ｉ）白金又はパラジウム並びに（ii）ランタン
と希土類金属及び遷移金属の中から選ばれた少なくとも
１種の金属との格子欠陥を有する複合酸化物を担持せし
めて成り、リーン時には窒素酸化物をランタンに吸着せ
しめ、ストイキ時及びリッチ時にその窒素酸化物を放出
して排気ガスを浄化する排気ガス浄化用触媒。(1) An exhaust gas purifying catalyst for simultaneously purifying carbon monoxide, hydrocarbons and nitrogen oxides in exhaust gas discharged from a lean burn engine. to become a carrier (i) platinum or palladium and (ii) lanthanum and rare earth Ri metal and formed by allowed carrying a composite oxide having a lattice defect and at least one metal selected from among transition metals, nitrogen during lean Adsorb oxide on lanthanum
Releases nitrogen oxides during stoichiometric and rich conditions
Exhaust gas purification catalyst that purifies exhaust gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00249293A JP3379125B2 (en) | 1993-01-11 | 1993-01-11 | Exhaust gas purification catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00249293A JP3379125B2 (en) | 1993-01-11 | 1993-01-11 | Exhaust gas purification catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06205975A JPH06205975A (en) | 1994-07-26 |
| JP3379125B2 true JP3379125B2 (en) | 2003-02-17 |
Family
ID=11530866
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00249293A Expired - Lifetime JP3379125B2 (en) | 1993-01-11 | 1993-01-11 | Exhaust gas purification catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3379125B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100341606C (en) * | 2005-06-20 | 2007-10-10 | 天津化工研究设计院 | Double functional deoxidation agent and production process thereof |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8530372B2 (en) | 2009-07-22 | 2013-09-10 | Basf Corporation | Oxygen storage catalyst with decreased ceria reduction temperature |
-
1993
- 1993-01-11 JP JP00249293A patent/JP3379125B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100341606C (en) * | 2005-06-20 | 2007-10-10 | 天津化工研究设计院 | Double functional deoxidation agent and production process thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06205975A (en) | 1994-07-26 |
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